The default behavior for adding and solving with noisemodels has changed from Pastas 1.5. Find more information here


interannual_variation(series, normalize=False)[source]#

Interannual variation after Martens et al. [2013].

  • series (pandas.Series) – Pandas Series with DatetimeIndex and head values.

  • normalize (bool, optional) – normalize the time series to values between zero and one.


Interannual variation (s).

Return type



The average between the range in annually averaged 3 highest monthly heads and the range in annually averaged 3 lowest monthly heads.

Inter-yearly variation of high and low water table (s):

s = ((max_HW - min_HW) + (max_LW - min_LW)) / 2

A higher value of s indicates a more variable head, and vice versa.


In this formulating the water table is referenced to a certain datum and positive, not as depth below the surface!